(a) Field of the Invention
The invention relates to a method and a system of driving a field effect transistor (FET) in a power stage and more particularly to a method and a system of driving a junction FET for providing a larger power by selecting the operating voltage range for the gate voltage.
(B) Description of the Prior Art
Among the junction type FET's, there are those which have pentode-like (saturated) characteristics and those which have triode-like (unsaturated) characteristics. In both of these junction-type FET's the gate voltage has been so selected as to be always of reverse polarity with respect to the junction between the gate and the source (channel) region. Particularly in the triode type junction FET's, however, the working range with the reverse gate voltage is limited with respect to the total range. Thus, the utilization rate of the power source voltage has not been satisfactory.
Thus, it has been desired, for the triode type junction FET's, to improve the power rating at least to the order of that of the pentode-type junction FET, and for the pentode type junction FET's to further improve the power rating.